Sizing and Desizing of Cotton and Polyester Yarns Using Liquid and Supercritical Carbon Dioxide with Nonfluorous CO2-Philes as Size Compounds

In this work, we demonstrate a completely green and economically viable sizing and desizing process for cotton and polyester yarns using liquid and supercritical CO2 as alternative solvent systems and inexpensive, nonfluorous CO2-philes as size compounds. The size performance of sucrose octaacetate (SOA), alpha-D-glucose pentaacetate (AGLU), and poly(ethylene glycol) (PEG) are studied. The mechanical properties of the sized yarn, as well as the optical and electron microscopic studies, are carried out to evaluate the quality of sizing. It is shown that SOA is the most suitable candidate as the size compound as it provides the best surface coverage and improved mechanical properties for the yarn, plausibly assisted by the formation of a smooth and glassy coating of SOA on the yarn. For AGLU and SOA, complete desizing is easily effected by virtue of their complete miscibility with liquid and supercritical CO2 at low pressures. It is observed that the desizing of the PEG-sized yarn is difficult due to the poor solubility of the size in the CO2-based solvent systems. The entire size materials and the solvent can be recycled, making it a zero-pollution technology that can easily be translated into industry at an affordable cost.